IoT devices usually equip with a single antenna for the sake of limited size, low cost and energy saving, which in turn hampers the exploitation of spatial multiplexing gain from MIMO technology. To combat this issue, virtual MIMO technology has emerged as an attractive candidate by coordinating multiple nodes to form one virtual antenna array entity [1]}, [2]}. The realization of virtual MIMO brings new challenges of data sharing, time/frequency synchronization, user grouping/clustering, and CSI estimation [3]}, [4]}. Nevertheless, it was disclosed in [5]}, [6]} that the virtual MIMO system surpasses the simple single-input single-output (SISO) system in terms of the consumed energy and delay. In [7]}, the virtual MIMO was proved to be a viable framework to improve the data rate and energy efficiency. Furthermore, experimental measurements were carried out for the virtual MIMO to confirm its throughput enhancement in indoor-to-outdoor scenarios in [8]}. In order to prolong the lifetime of IoT networks as well as improve its capacity, the application of virtual MIMO to IoT has received an ever-increasing research attention recently[9]}, [10]}, [11]}, [12]}. To name a few, in [9]}, a multi-antenna unmanned aerial vehicle (UAV) serves as an on-demand flexible platform, which communicates with a cluster of single-antenna IoT devices through a virtual MIMO link. In [10]}, a virtual MIMO approach was invented for the delivery of sensor data to a distant sink node in wireless body area networks (WBAN).
